v. 1. Ancient world to A.D. 400.--v. 2. Middle Age, 400-1250.--v. 3. Eve of the modern world, 1250-1648.--v. 4. Early modern era, 1648-1770.--v. 5. Age of Revolution, 1770-1870.--v. 6. War and totalitarianism, 1870 to the present.